This invention relates to methods of and apparatus for applying strands to a support and particularly relates to methods of and apparatus for applying resin-treated multiple-fiber strands to a mandrel mounted for receipt of strands.
In one process for manufacturing products having hollow shafts, such as shafts for golf clubs, fishing rods and the like, strands of multiple fibers are passed through a bath containing a resin. The resin-treated strands are eventually wrapped onto a mandrel of small diameter which defines the core size and shape of the ultimate shaft and provides support for the wrapped strands during a curing process. After the resin has cured, the mandrel is removed from assembly with the cured product to provide the shaft.
In some instances, the mandrel is a solid shaft of definitive length and tapers from one end to the other. Thus, the resulting product will be hollow when the mandrel is removed and the product will be tapered in accordance with the taper of the mandrel. In other instances, the solid mandrel may be of uniform diameter from one end to the other whereby the core size or diameter of the resulting product is also of uniform diameter.
When preparing for the strand wrapping process, the solid mandrel is typically mounted into an apparatus where one end of the mandrel is gripped, for example, within a rotatable chuck, and the opposite end is gripped or is centered on a dead spindle. In any event, the mandrel is mounted at opposite ends thereof in such a manner that axially compressive forces are applied to the mandrel from opposite ends thereof. The strand is passed through a head which is mounted for movement relative to and generally in a path parallel to the axis of the mandrel which is rotated through the rotatable chuck.
The lead end of the strand is attached to the mandrel and the head is moved along the mandrel while the mandrel is rotated whereby the strand is wrapped onto the mandrel in a helical pattern from one end of the mandrel to the other. Adjustment of the linear speed of the head and/or the rotational speed of the mandrel allows for selection of the angle of the helical wrapping.
The application of compressive forces at the ends of the mandrel as noted above causes the mandrel of small diameter to bow from its at-rest linear axial position. This causes the angle of the helical wrapping to vary as the head moves from one end of the mandrel to the other.
In an attempt to resolve the problem of bowing of the mandrel, the one end of the mandrel which was assembled with the dead spindle is mounted in a gripping device which applies a tensile load to that end of the mandrel. This tensioning force tends to pull the mandrel along its axis and attempts to hold the mandrel in a linear axial state consistent with its at-rest axial state while the strand is being wrapped onto the mandrel. In mass manufacturing processes utilizing the tensile-load technique, the time for loading and unloading the mandrels is increased in comparison to the technique in which only one end is gripped. Consequently, while the tensile-load technique appears to be a solution to the problem of mandrel bowing, it increases the cost of manufacture and decreases the volume of product capable of being made within a defined period.
Thus, there is a need for methods of and apparatus for facilitating the manufacture of shafts while avoiding the above-noted mandrel-mounting problems associated with the bowing of the mandrel and the expensive and time-consuming tensile-load technique.